用户在编辑视图中单击保存按钮后，如何将文件上传到文件系统并将路径保存到数据库？
How do I upload file to file system and save path to database AFTER user clicks save button in Edit view?
我想在编辑视图中按下“保存”按钮后将我的文件上传到文件系统。为此，我尝试在编辑 (POST) 操作中调用 UploadToFileSystem 方法。
我学会了如何做到这一点 here but this tutorial 向您展示了如何在索引操作网格视图中做到这一点。我一直在尝试对该逻辑进行逆向工程，以便在编辑操作中做到这一点。
这就是我在仅使用该方法的按钮中调用 UploadToFileSystem 之前的样子，它可以将路径保存到文件系统而不是数据库。
我会给你一个 Github link 的应用程序，但它有很多依赖项，你需要安装并获得访问权限。
之前：
Debugging in VS Code showing UploadToFileSystem being called by itself.
之后：（它不起作用的地方。）
Debugging in VS Code showing UploadToFileSystem being called by itself.
因此，在第二张图片中显示没有检索到文件的错误之后，我尝试使用名为 ProblemInputModel 的视图模型，但是一旦文件传递到视图，我就会收到空引用异常。
ProblemsController.cs
// POST: Problems/Edit/5
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Edit(int id, [Bind("ID,ProblemTitle,ProblemDescription,ProblemStartDate,ProblemFileAttachments,ProblemSeverity,ProblemComplete")] Problem problem, List<IFormFile> iFormFile)
{
//Used for file attachment upload.
if (id != problem.ID)
{
return NotFound();
}
if (ModelState.IsValid)
{
try
{
_context.Update(problem);
await _context.SaveChangesAsync();
//Upload or update any attachments user inserted.
await UploadToFileSystem(iFormFile ,problem.ID, problem.ProblemTitle, problem.ProblemDescription,
problem.ProblemStartDate, problem.ProblemSeverity);
}
catch (DbUpdateConcurrencyException)
{
if (!ProblemExists(problem.ID))
{
return NotFound();
}
else
{
throw;
}
}
return RedirectToAction(nameof(Index));
}
return View(problem);
}
[HttpPost]
public async Task<IActionResult> UploadToFileSystem(List<IFormFile> files, int? id, string title,
string description, DateTime dateTime, int severity)
{
foreach (var file in files)
{
//Get the base Path, i.e, The Current Directory of the application + /Files/.
var basePath = Path.Combine(Directory.GetCurrentDirectory() + "\Files\");
//Checks if the base path directory exists, else creates it.
bool basePathExists = System.IO.Directory.Exists(basePath);
if (!basePathExists) Directory.CreateDirectory(basePath);
//Gets the file name without the extension.
var fileName = Path.GetFileNameWithoutExtension(file.FileName);
//Combines the base path with the file name.
var filePath = Path.Combine(basePath, file.FileName);
//If the file doesnt exist in the generated path, we use a filestream object, and create a new file, and then copy the contents to it.
var extension = Path.GetExtension(file.FileName);
if (!System.IO.File.Exists(filePath))
{
using (var stream = new FileStream(filePath, FileMode.Create))
{
await file.CopyToAsync(stream);
}
//Create a new Problem object with required values.
var problem = await _context.Problems.FindAsync(id);
problem = new Problem
{
ProblemFileAttachments = filePath,
ProblemTitle = title,
ProblemDescription = description,
ProblemStartDate = dateTime,
ProblemSeverity = severity
};
//Inserts this model to the db via the context instance of EF Core.
_context.Problems.Add(problem);
_context.SaveChanges();
}
}
//Loads all the File data to an object and sets a message in the TempData.
TempData["Message"] = "File successfully uploaded to File System.";
return RedirectToAction("Index");
}
Edit.cshtml
@model Pitcher.Models.Problem
@{
ViewData["Title"] = "Edit";
}
<h1>Edit</h1>
<h4>Problem</h4>
<hr />
<div class="row">
<div class="col-md-4">
<form asp-action="Edit" enctype="multipart/form-data" method="post">
<div asp-validation-summary="ModelOnly" class="text-danger"></div>
<div class="form-group">
<label asp-for="ID" class="control-label" ></label>
<input asp-for="ID" readonly="true" disabled="true" class="form-control"/>
</div>
<div class="form-group">
<label asp-for="ProblemTitle" class="control-label"></label>
<input asp-for="ProblemTitle" class="form-control" />
<span asp-validation-for="ProblemTitle" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="ProblemDescription" class="control-label"></label>
<textarea asp-for="ProblemDescription" class="form-control" rows="10" cols="50"></textarea>
<span asp-validation-for="ProblemDescription" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="ProblemStartDate" class="control-label"></label>
<input asp-for="ProblemStartDate" class="form-control" />
<span asp-validation-for="ProblemStartDate" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="ProblemFileAttachments" class="control-label"></label>
<input asp-for="ProblemFileAttachments" type="file" name="files"/>
@* <button type="submit" class="btn btn-primary" asp-controller="Problems" asp-action="UploadToFileSystem">Upload to File System</button> *@
</div>
<div class="form-group">
<label asp-for="ProblemSeverity" class="control-label"></label>
<select asp-for="ProblemSeverity" class="form-control">
<option value="">Choose severity level</option>
<option value="1">Very Low</option>
<option value="2">Low</option>
<option value="3">Medium</option>
<option value="4">High</option>
<option value="5">Very High</option>
</select>
<span asp-validation-for="ProblemSeverity" class="text-danger"></span>
</div>
<div class="form-group form-check">
<label class="form-check-label">
<input class="form-check-input" asp-for="ProblemComplete" /> @Html.DisplayNameFor(model => model.ProblemComplete)
</label>
</div>
<div class="form-group" method="post">
<input type="submit" value="Save" class="btn btn-primary" />
</div>
</form>
</div>
</div>
<div>
<a asp-action="Index">Back to List</a>
</div>
@section Scripts {
@{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}
Problem.cs
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.ComponentModel.DataAnnotations;
namespace Pitcher.Models
{
public class Problem
{
public int ID {get;set;}
[Required]
[StringLength(180, MinimumLength = 2, ErrorMessage = "Problem Title must be bettween 2 to 20 characters.")]
[DataType(DataType.Text)]
[Display(Name = "Problem Title")]
[Column("ProblemTitle")]
public string ProblemTitle {get;set;}
[Required]
[StringLength(int.MaxValue, MinimumLength = 5, ErrorMessage = "Problem Title must be at least 5 characters.")]
[DataType(DataType.Text)]
[Display(Name = "Problem Description")]
[Column("ProblemDescription")]
public string ProblemDescription {get;set;}
[Required]
[DataType(DataType.Date)]
[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
[Display(Name = " Problem Start Date")]
[Column("ProblemStartDate")]
public DateTime ProblemStartDate {get;set;}
[DataType(DataType.Upload)]
[Display(Name = " Upload file")]
[Column("ProblemFileAttachments")]
public string ProblemFileAttachments {get;set;}
[Required]
[Display(Name = "Problem Severity")]
[Range(1,5, ErrorMessage
= "Problem Severity value for {0} must be between {1} and {2}.")]
[Column("ProblemSeverity")]
public int ProblemSeverity {get;set;}
[Display(Name = "Problem Complete")]
[Column("ProblemComplete")]
public bool ProblemComplete {get;set;}
public ICollection<Result> Result {get;set;}
public ICollection<Chat> Chat {get;set;}
//public List<Problem> ProblemFileModel {get; set;}
}
}
问题输入模型
//This is a view model only.
public class ProblemInputModel
{
[DataType(DataType.Upload)]
[Display(Name = " Upload file")]
[Column("ProblemFileAttachments")]
public List<IFormFile> ProblemFileAttachments {get;set;}
}
这两种情况，都是模型绑定失败导致的，都得到null值
您需要了解以下两点：
ASP.NET Core Tag Helper asp-for 将生成 id 和 name 属性。
模型绑定系统在来源中查找名称模式 prefix.property_name。如果什么都找不到，它只查找没有前缀的 property_name。
此处模型绑定失败是因为name属性与参数名不匹配
第一种情况到直接调用UploadToFileSystem方法，得到空参数：
[HttpPost]
public IActionResult UploadToFileSystem(List<IFormFile> files, int? ID, string ProblemTitle,
string ProblemDescription, DateTime ProblemStartDate, int ProblemSeverity)
{
//.......
return RedirectToAction("Index");
}
第二种情况调用UploadToFileSystem方法insideEdit动作：
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Edit(int id, [Bind("ID,ProblemTitle,ProblemDescription,ProblemStartDate,ProblemFileAttachments,ProblemSeverity,ProblemComplete")] Problem problem,
List<IFormFile> files) //change here...
{
//.......
return View(problem);
}
如果要使用ProblemInputModel模型，需要先修改视图代码去掉name="files"，然后asp-for会生成name="ProblemFileAttachments"匹配ProblemFileAttachments 属性 在 ProblemInputModel 型号中：
<input asp-for="ProblemFileAttachments" type="file" @*name="files"*@/>
然后记得添加ProblemInputModel模型作为参数：
public IActionResult Edit(int id, [Bind("ID,ProblemTitle,ProblemDescription,ProblemStartDate,ProblemFileAttachments,ProblemSeverity,ProblemComplete")] Problem problem,
ProblemInputModel model)
我想在编辑视图中按下“保存”按钮后将我的文件上传到文件系统。为此，我尝试在编辑 (POST) 操作中调用 UploadToFileSystem 方法。
我学会了如何做到这一点 here but this tutorial 向您展示了如何在索引操作网格视图中做到这一点。我一直在尝试对该逻辑进行逆向工程，以便在编辑操作中做到这一点。
这就是我在仅使用该方法的按钮中调用 UploadToFileSystem 之前的样子，它可以将路径保存到文件系统而不是数据库。
我会给你一个 Github link 的应用程序，但它有很多依赖项，你需要安装并获得访问权限。
之前：
Debugging in VS Code showing UploadToFileSystem being called by itself.
之后：（它不起作用的地方。）
Debugging in VS Code showing UploadToFileSystem being called by itself.
因此，在第二张图片中显示没有检索到文件的错误之后，我尝试使用名为 ProblemInputModel 的视图模型，但是一旦文件传递到视图，我就会收到空引用异常。
ProblemsController.cs
// POST: Problems/Edit/5
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Edit(int id, [Bind("ID,ProblemTitle,ProblemDescription,ProblemStartDate,ProblemFileAttachments,ProblemSeverity,ProblemComplete")] Problem problem, List<IFormFile> iFormFile)
{
//Used for file attachment upload.
if (id != problem.ID)
{
return NotFound();
}
if (ModelState.IsValid)
{
try
{
_context.Update(problem);
await _context.SaveChangesAsync();
//Upload or update any attachments user inserted.
await UploadToFileSystem(iFormFile ,problem.ID, problem.ProblemTitle, problem.ProblemDescription,
problem.ProblemStartDate, problem.ProblemSeverity);
}
catch (DbUpdateConcurrencyException)
{
if (!ProblemExists(problem.ID))
{
return NotFound();
}
else
{
throw;
}
}
return RedirectToAction(nameof(Index));
}
return View(problem);
}
[HttpPost]
public async Task<IActionResult> UploadToFileSystem(List<IFormFile> files, int? id, string title,
string description, DateTime dateTime, int severity)
{
foreach (var file in files)
{
//Get the base Path, i.e, The Current Directory of the application + /Files/.
var basePath = Path.Combine(Directory.GetCurrentDirectory() + "\Files\");
//Checks if the base path directory exists, else creates it.
bool basePathExists = System.IO.Directory.Exists(basePath);
if (!basePathExists) Directory.CreateDirectory(basePath);
//Gets the file name without the extension.
var fileName = Path.GetFileNameWithoutExtension(file.FileName);
//Combines the base path with the file name.
var filePath = Path.Combine(basePath, file.FileName);
//If the file doesnt exist in the generated path, we use a filestream object, and create a new file, and then copy the contents to it.
var extension = Path.GetExtension(file.FileName);
if (!System.IO.File.Exists(filePath))
{
using (var stream = new FileStream(filePath, FileMode.Create))
{
await file.CopyToAsync(stream);
}
//Create a new Problem object with required values.
var problem = await _context.Problems.FindAsync(id);
problem = new Problem
{
ProblemFileAttachments = filePath,
ProblemTitle = title,
ProblemDescription = description,
ProblemStartDate = dateTime,
ProblemSeverity = severity
};
//Inserts this model to the db via the context instance of EF Core.
_context.Problems.Add(problem);
_context.SaveChanges();
}
}
//Loads all the File data to an object and sets a message in the TempData.
TempData["Message"] = "File successfully uploaded to File System.";
return RedirectToAction("Index");
}
Edit.cshtml
@model Pitcher.Models.Problem
@{
ViewData["Title"] = "Edit";
}
<h1>Edit</h1>
<h4>Problem</h4>
<hr />
<div class="row">
<div class="col-md-4">
<form asp-action="Edit" enctype="multipart/form-data" method="post">
<div asp-validation-summary="ModelOnly" class="text-danger"></div>
<div class="form-group">
<label asp-for="ID" class="control-label" ></label>
<input asp-for="ID" readonly="true" disabled="true" class="form-control"/>
</div>
<div class="form-group">
<label asp-for="ProblemTitle" class="control-label"></label>
<input asp-for="ProblemTitle" class="form-control" />
<span asp-validation-for="ProblemTitle" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="ProblemDescription" class="control-label"></label>
<textarea asp-for="ProblemDescription" class="form-control" rows="10" cols="50"></textarea>
<span asp-validation-for="ProblemDescription" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="ProblemStartDate" class="control-label"></label>
<input asp-for="ProblemStartDate" class="form-control" />
<span asp-validation-for="ProblemStartDate" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="ProblemFileAttachments" class="control-label"></label>
<input asp-for="ProblemFileAttachments" type="file" name="files"/>
@* <button type="submit" class="btn btn-primary" asp-controller="Problems" asp-action="UploadToFileSystem">Upload to File System</button> *@
</div>
<div class="form-group">
<label asp-for="ProblemSeverity" class="control-label"></label>
<select asp-for="ProblemSeverity" class="form-control">
<option value="">Choose severity level</option>
<option value="1">Very Low</option>
<option value="2">Low</option>
<option value="3">Medium</option>
<option value="4">High</option>
<option value="5">Very High</option>
</select>
<span asp-validation-for="ProblemSeverity" class="text-danger"></span>
</div>
<div class="form-group form-check">
<label class="form-check-label">
<input class="form-check-input" asp-for="ProblemComplete" /> @Html.DisplayNameFor(model => model.ProblemComplete)
</label>
</div>
<div class="form-group" method="post">
<input type="submit" value="Save" class="btn btn-primary" />
</div>
</form>
</div>
</div>
<div>
<a asp-action="Index">Back to List</a>
</div>
@section Scripts {
@{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}
Problem.cs
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.ComponentModel.DataAnnotations;
namespace Pitcher.Models
{
public class Problem
{
public int ID {get;set;}
[Required]
[StringLength(180, MinimumLength = 2, ErrorMessage = "Problem Title must be bettween 2 to 20 characters.")]
[DataType(DataType.Text)]
[Display(Name = "Problem Title")]
[Column("ProblemTitle")]
public string ProblemTitle {get;set;}
[Required]
[StringLength(int.MaxValue, MinimumLength = 5, ErrorMessage = "Problem Title must be at least 5 characters.")]
[DataType(DataType.Text)]
[Display(Name = "Problem Description")]
[Column("ProblemDescription")]
public string ProblemDescription {get;set;}
[Required]
[DataType(DataType.Date)]
[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
[Display(Name = " Problem Start Date")]
[Column("ProblemStartDate")]
public DateTime ProblemStartDate {get;set;}
[DataType(DataType.Upload)]
[Display(Name = " Upload file")]
[Column("ProblemFileAttachments")]
public string ProblemFileAttachments {get;set;}
[Required]
[Display(Name = "Problem Severity")]
[Range(1,5, ErrorMessage
= "Problem Severity value for {0} must be between {1} and {2}.")]
[Column("ProblemSeverity")]
public int ProblemSeverity {get;set;}
[Display(Name = "Problem Complete")]
[Column("ProblemComplete")]
public bool ProblemComplete {get;set;}
public ICollection<Result> Result {get;set;}
public ICollection<Chat> Chat {get;set;}
//public List<Problem> ProblemFileModel {get; set;}
}
}
问题输入模型
//This is a view model only.
public class ProblemInputModel
{
[DataType(DataType.Upload)]
[Display(Name = " Upload file")]
[Column("ProblemFileAttachments")]
public List<IFormFile> ProblemFileAttachments {get;set;}
}
这两种情况，都是模型绑定失败导致的，都得到null值
您需要了解以下两点：
ASP.NET Core Tag Helper
asp-for将生成id和name属性。模型绑定系统在来源中查找名称模式
prefix.property_name。如果什么都找不到，它只查找没有前缀的property_name。
此处模型绑定失败是因为name属性与参数名不匹配
第一种情况到直接调用UploadToFileSystem方法，得到空参数：
[HttpPost]
public IActionResult UploadToFileSystem(List<IFormFile> files, int? ID, string ProblemTitle,
string ProblemDescription, DateTime ProblemStartDate, int ProblemSeverity)
{
//.......
return RedirectToAction("Index");
}
第二种情况调用UploadToFileSystem方法insideEdit动作：
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Edit(int id, [Bind("ID,ProblemTitle,ProblemDescription,ProblemStartDate,ProblemFileAttachments,ProblemSeverity,ProblemComplete")] Problem problem,
List<IFormFile> files) //change here...
{
//.......
return View(problem);
}
如果要使用ProblemInputModel模型，需要先修改视图代码去掉name="files"，然后asp-for会生成name="ProblemFileAttachments"匹配ProblemFileAttachments 属性 在 ProblemInputModel 型号中：
<input asp-for="ProblemFileAttachments" type="file" @*name="files"*@/>
然后记得添加ProblemInputModel模型作为参数：
public IActionResult Edit(int id, [Bind("ID,ProblemTitle,ProblemDescription,ProblemStartDate,ProblemFileAttachments,ProblemSeverity,ProblemComplete")] Problem problem,
ProblemInputModel model)